//转换常数
	var x_pi = 3.14159265358979324 * 3000.0 / 180.0;
    var pi = 3.14159265358979324;
    var a = 6378245.0;
    var ee = 0.00669342162296594323;
 
    function transformLon(x, y) {
        var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
        ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
        return ret;
    };
    
    function transformLat(x, y) {
        var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
        ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
        return ret;
    }
    
    function outOfChina(lat, lon) {
        if (lon < 72.004 || lon > 137.8347)
            return true;
        if (lat < 0.8293 || lat > 55.8271)
            return true;
        return false;
    }
    
/*    
 * WGS-84：是国际标准，GPS坐标（Google Earth使用、或者GPS模块、天地图）
 * GCJ-02：中国坐标偏移标准，Google Map、高德、腾讯使用
 * BD-09：百度坐标偏移标准，Baidu Map使用
*/
    
    /**
     * wgLat 纬度
     * wgLon 经度
     * WGS-84 到 GCJ-02 的转换（即 GPS 加偏）
     * */
    function wgs_gcj_encrypts(wgLat1, wgLon1) {
		let wgLat = wgLon1;
		let wgLon = wgLat1;
        var point={};
        if (outOfChina(wgLat, wgLon)) {
            point.lat=wgLat;
            point.lng=wgLon;
            return point;
        }
        var dLat = transformLat(wgLon - 105.0, wgLat - 35.0);
        var dLon = transformLon(wgLon - 105.0, wgLat - 35.0);
        var radLat = wgLat / 180.0 * pi;
        var magic = Math.sin(radLat);
        magic = 1 - ee * magic * magic;
        var sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
        dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
        var lat = wgLat + dLat;
        var lon = wgLon + dLon;
        point.lat=lat;
        point.lon=lon;
        return [lon,lat];
    };
    
    
    /**
     * wgLat 纬度
     * wgLon 经度
     * BD-09转换GCJ-02
     * 百度转google
     * */
    function bd_google_encrypt(bd_lat, bd_lon){
    	var point={};
        var x = bd_lon - 0.0065;
        var y = bd_lat - 0.006;  
        var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * x_pi);  
        var theta =Math.atan2(y, x) - 0.000003 * Math.cos(x * x_pi);  
        var gg_lon = z * Math.cos(theta);  
        var gg_lat = z * Math.sin(theta);  
        point.lat=gg_lat;
        point.lon=gg_lon;
        return point;
    };
    
 
    /**
     * gg_lat 纬度
     * gg_lon 经度
     * GCJ-02转换BD-09
     * Google地图经纬度转百度地图经纬度
     * */
    function google_bd_encrypt(gg_lat, gg_lon){
        var point={};
        var x = gg_lon;
        var y = gg_lat;
        var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * x_pi);
        var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * x_pi); 
        var bd_lon = z * Math.cos(theta) + 0.0065;
        var bd_lat = z * Math.sin(theta) + 0.006;
        point.lat=bd_lat;
        point.lon=bd_lon;
        return point;
    };

export{
	wgs_gcj_encrypts
}